Currently, a number of consumer electronic devices include internal speakers and are adapted to output audio signals including speech and music via speaker ports. An internal speaker comprises a speaker box and a speaker driver. The speaker box is an acoustic chamber that includes the speaker port and at least partially encloses a speaker driver. The speaker driver includes a diaphragm, a voice coil, a magnet unit and a yoke.
For audio to be played, current is applied to the speaker driver which also causes the voice coil to generate heat. The voice coil in the speaker driver is coupled to the magnet unit and thus, the heat from the voice coil is transferred to the magnet unit. The amount of power that may be applied to the speaker box is limited by the resilience of the magnet unit and the voice coil to heat. Exposing too much heat to the voice coil may cause (i) the voice coil wire to short or burn due to the bonding material melting around the wire, (ii) suspension surround softening or breaking, and (ii) diaphragm dome delaminating and softening. Overheating any magnet will cause structural or mechanical damage to the magnet and may result in its demagnetization. Accordingly, the temperature of the voice coil needs to be monitored to ensure that the integrity of the speaker is maintained.